The Swan of Tuonela, finnish national poem KALEVALA. Why a Swan?

In finland the Swan is a very important animal in culture and mythology.
It is prohibited to hunt.

The Petroglyph showed from the great work of antti lahela is NOT (!) representing an actual Swan. It replicates what the people of the time have seen in the sky with their very own eyes. It impressed them so much that they had the urge to make a mark to remind all those after them that the sky can change dramatically.
It is pure coincidence that it looks like a Swan. Meaning that: first was the figure in the sky and after that came the easily understandable association with the Swan as a bird.
So, the deep respect towards this bird in finnish culture can be explained by the even deeper respect or even fear of extinction of the people who made those paintings, wich where the very witnesses of the happenings in their sky.